1. Field of the Invention
The present invention relates to display devices and more particularly to a liquid crystal display device and a method of fabricating the same.
2. Discussion of the Related Art
Recently, various mobile-type electronic devices, such as mobile phones, PDAs, notebook computers, have become widely used, and there is increasing demand for a thin and light flat panel display device. Examples of flat panel display devices include liquid crystal display (LCD) devices, plasma display panels PDP, field emission displays FED, and vacuum fluorescent displays VFD. Among the various examples of flat panel display devices, the liquid crystal display (LCD) device has attracted great attention due to advantages such as its suitability for mass production, simple driving means, and high resolution and picture quality.
FIG. 1 is a cross section view illustrating a liquid crystal display device according to the related art. As shown in FIG. 1, the liquid crystal display device 1 according to the related art includes a lower substrate 5, an upper substrate 3, and a liquid crystal layer 7 formed between the lower substrate 5 and the upper substrate 3.
The lower substrate 5 corresponds to a thin film transistor array substrate, which includes a plurality of pixel regions, wherein a thin film transistor is formed in each of the pixel region.
The upper substrate 3 corresponds to a color filter substrate, which includes a color filter layer to realize colors.
Pixel electrodes and a common electrode are formed on the lower substrate 5 and the upper substrate 3, respectively. In addition, the lower and upper substrates 5 and 3 are coated with alignment films to align liquid crystal molecules included in the liquid crystal layer 7.
Spacers 9 are provided between the lower substrate 5 and the upper substrate 3, to maintain a cell gap therebetween. The liquid crystal layer 7 is formed between the lower substrate 5 and the upper substrate 3. Accordingly, as the liquid crystal molecules included in the liquid crystal layer 7 are driven by the thin film transistors formed on the lower substrate 5, an amount of light passing through the liquid crystal layer is controlled so that information is displayed.
The liquid crystal display device uses electro-optic effects resulting from anisotropy of the liquid crystal associated with the alignment of liquid crystal molecules. Accordingly, the display stability of a liquid crystal display device is largely affected by the control of the alignment of liquid crystal molecules.
The processes for forming the alignment film to align the liquid crystal molecules and for forming the spacers to maintain the cell gap with a seal pattern greatly affect the picture quality in the liquid crystal cell.
When the spacers are scattered by a related art method, the spacers may exist in the pixel region through which light is transmitted to display an image. The spacers in the pixel region may disturb the alignment of liquid crystal, and may lower an aperture ratio of the liquid crystal cell. Accordingly, the density of spacers is controlled to be below a predetermined level. Additionally, it is desirable to uniformly distribute the spacers over an entire screen.
A high density of spacers is useful for maintaining the cell gap between the two substrates. Employing a high density of spacers may deteriorate the ability of the display to display black, lowering a contrast ratio of the display because the spacers cause dispersion of light and disorder of the alignment of liquid crystal in the area surrounding the spacer.
In order to overcome this problem, a method of providing column spacers has been proposed recently in which the spacers are directly patterned on the lower or upper substrate. The column spacers of the related art can be fabricated by depositing or coating organic polymer material on a substrate and carrying out photolithography to selectively remove portions of the deposited or coated organic polymer material.
Photolithography includes coating, exposure and development of photoresist, thereby requiring using an additional mask resulting in a more complex manufacturing process and in an increase in manufacturing costs.